This comment has been minimized.

Thanks. Programs that contain assembly code don't build with both gc and gccgo. That is because gc uses a non-standard assembly syntax based on the Plan 9 assembler, and also uses a non-standard calling convention. Assembler code written for gc won't work with gccgo.

Fortunately this code has a non-assembler version, so it should be possible to use that with the gccgo build tag. I'll look into that.